In a linear guide device, a rolling element cage 24 holding balls interposed between a rail side rolling element rolling groove and a slider side rolling element rolling groove is formed of a synthetic resin material, and has two plate parts 244 facing to each other with a slider body being held therebetween. The rolling element cage 24 has a positioning part that makes contact with the inside surface of the slider body and is positioned on the slider body by the positioning part with respect to the slider.